Shape Optimization for the Design of Linear and Nonlinear Metamaterials | NDE 2021

#NDT #UltrasonicTesting #LinearMetamaterials #NonlinearMetamaterials #HarmonicScattering #FiniteElementAnalysis #COMSOL Research presentation delivered for NDE 2021 Virtual Conference & Exhibition by the Indian Society for NDT (ISNDT), published in eJNDT Vol. 27(4). https://www.ndt.net/search/docs.php?i... Title of the Contribution "Shape Optimization for the Design of Linear and Nonlinear Metamaterials to Improve Nonlinear Ultrasonic Testing" Abstract Monochromatic ultrasonic bulk waves generate higher harmonics upon interacting with early-stage material defects like microcracks and dislocations. However, system-generated higher harmonics from transducers, instrumentation, inconsistent clamping forces, and couplants often mask these true damage signatures. To eliminate such parasitic harmonics, layered phononic metamaterials are used to create bandgaps. Calculating optimal geometric parameters through manual parametric sweeps is exceptionally challenging and time-consuming. This study formulates an automated shape optimization framework using non-gradient algorithms integrated between MATLAB and COMSOL. By selecting steel and glass for their bandgap structures, the optimization process minimizes higher-harmonic amplitudes (2f, 3f, 4f) while controlling energy diversion, fully automating the forward finite element solution and inverse layer-thickness optimization under weak constraints. The flow of the Presentation: 0:00 Introduction to Nonlinear Ultrasonic Testing and Parasitic System Harmonics 2:15 Motivation: Masking Effects Caused by Instrumentation, Transducers, and Couplants 4:30 Phononic Bandgaps and Layered Metamaterial Design Principles 6:45 Formulation of the Shape Optimization Problem for Linear and Nonlinear Devices 9:10 Numerical Implementation: Coupling MATLAB and COMSOL for Automated Optimization 11:35 Results: Harmonic Suppression (2f, 3f, 4f) and Optimal Steel-Glass Layer Thicknesses 13:50 Conclusion and Summary of Applicability in NDE Note: This conference presentation summarizes peer-reviewed research published in the e-Journal of Nondestructive Testing (eJNDT), linking advanced optimization techniques with structural wave mechanics. For other research details: https://sites.google.com/view/pravink... #PravinkumarGhodake #NDE2021 #ISNDT #eJNDT #NDT #UltrasonicTesting #LinearMetamaterials #NonlinearMetamaterials #HarmonicScattering #FiniteElementAnalysis #COMSOL #SolidMechanics #MechanicalEngineering #IITBombay #ResearchScholar #Research